We have continued to focus our research studies on the etiology, immunology, pathology, molecular biology, biochemistry, protein chemistry, and molecular genetics of subacute progressive degenerative diseases of the nervous system. Particular emphasis is placed on a group of rare diseases which we have identified as the transmissible spongiform encephalopathies (TSEs). This group consists of four human diseases--kuru, Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker diseases (GSS), and fatal familial insomnia (FFI); and five diseases of animals--scrapie, transmissible mink encephalopathy (TME), chronic wasting disease of deer and elk (CWD), feline spongiform encephalopathy (FSE) and bovine spongiform encephalopathy (BSE). Previous work demonstrated that these diseases are cerebral amyloidoses caused by posttranslational modification of a specific host precursor sialoglycoprotein resulting in the formation of amyloid fibrils. The human diseases occur sporadically (80%), iatrogenically (2%) or as autosomal dominant genetic/infectious diseases (10%). A number of point mutations have been identified which significantly increase the probability of the conversion of the cellular protein to an infectious polypeptide. We continued to study the range and sensitivity of monoclonal or polyclonal anti-PrP antibodies and have used them to examine blood and CSF samples to develop a better diagnostic assay.